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24V pump start relay.

I just replaced a timer for an individual and learned an important lesson. The system has ThermoHydrolic valves, which require a different power supply than all current digital timers offer. Fortunatly for me, I didn't cook the timer before I realized the problem. I've been advised that I need to use a second power supply that has 24V 3+amps and a relay that is triggered off the common to send the power from the second supply to the valves. I'm have a horrible time trying to find a relay to accomidate this. The customer would prefer doing this as to digging up 6 valves that are 30+ years old. Anyone ever run across this and have a part or part number that would solve this?

You don't need one relay. You need a relay for each valve in the system. Or you need to find another electromechanical controller, and good luck with that.

You might do some testing to see whether a more conventional 40 VA step-down transformer will be good enough. If not, you will have to pony up for something bigger, like the 75 VA units I have set aside for such occasions.

I still have the controller and it still functions. The client wanted the newer digital timer because they are easier to operate. So I have basically 3 options; replace all of the valves, get 6 relays (5 zones and a master), or find the needed wiring harnesses to make the old timer function again. This problem is getting worse by the minute.

After talking with a local expert that has run into this exact problem, the plan sounds like wiring an ice maker relay in with the second power supply and the common and master valve zones. This should allow the system to power up on the old power supply and not the timer supply (which can't handle the valves). Just waiting on him to provide the wiring diagram on how to do it and then I will complete the job (hopefully).

Wet, I would disconnect the MV, but these valves are buried with no valve boxes, as was the standard in the area in 1976.

I would think it would. Based on the information I've gathered, the Thermo Hydrolic valves require 2 or 3 amps of power vs the 0.75 amps the current timers put out. That "overdraw" is what is causing the timer to error out currently.